The food processing industry employs vast quantities of water to create purified food products. Among the food industries with high volumes of water requirements are the sugar cane, sugar beet processing, fruit and vegetable processing, meat and poultry processing, grain processing, fat and oil processing and dairy product processing industries. Unit operations which are most common to the various types of food processing listed above include boiling and cooling. Boiling or cooling operations have a high demand for make-up water. Much of that water could be re-used in processing operations of it is sufficiently purifies. However, there are strict requirements imposed upon this purification process imposed by the FDA, which limit the choice of chemicals for recycle water treatment.
The first step toward the purification of food processing recyclable waters is the detection of those impurities present in the food processing stream which must be removed. Once that determination has been made, appropriate steps may be taken to purify the water, or to prevent contaminations altogether whenever possible. It must be noted that any method for detection of impurities must also conform to FDA requirements if it involves a chemical additive to the water utilized for the processing of food. Therefore, there is an ongoing need for FDA-acceptable methods of detection of impurities.
The problems associated with the recycling of make-up water for boilers may be taken as exemplary in the evaluation of the need for efficient methods for detection of impurities in the food processing system. Boiler feedwater, which normally is comprised of both makeup water and recirculated condensate water, contains some impurities regardless of the extent to which such waters are treated before being fed to a boiler. When steam is generated, substantially pure water vapor is discharged from the boiler, leaving the impurities (the dissolved and suspended solids) behind, which results in the increase of their concentration in the boiler water. The discharged steam is replaced by contaminant-containing feedwater. An ever increasing concentration of dissolved and suspended solids in the boiler water inevitably results in very serious problems, including deposit formation, corrosion, foaming and carry over, decreased heat transfer efficiency, boiler tube failure or occlusion, for example. Boiler-impurities concentration (boiler solids concentration) is offset by withdrawing water as normal blowdown. The heat energy in the normal blowdown, however, is a major factor reducing a boiler's thermal efficiency, and therefore a blowdown rate in excess of that required to limit solids concentration should be avoided. An excessive blowdown rate also unnecessarily increases water costs.
The use of inert tracer materials to monitor and control the concentration of treatment chemical products (e.g., those containing corrosion and scale inhibitors) in industrial water systems is well-known. Hoots (U.S. Pat. No. 4,783,314) discloses the use of inert tracer materials for monitoring and controlling the concentration of treatment chemical products, corrosion and scale inhibitors, using fluorometry. Hoots et at. (U.S. Pat. Nos. 4,966,711 and 5,041,386) teaches the use of inert fluorescent additives which are added in direct proportion to the amount of a corrosion and/or scale inhibitor to monitor the concentration of a corrosion and/or scale inhibitor in a given industrial water system. U.S. Pat. Nos. 4,992,380; 5,006,311; 5,132,096 and 5,320,967 disclose methods and equipment to monitor fluorescent tracers used in industrial water treatment applications.
Leak detection for temperature-conditioning fluids of the food processing industry among others are disclosed in Hoots et al. U.S. Pat. Nos. 5,304,800 and 5,416,323.
Additionally, Hoots et al. (U.S. Pat. Nos. 5,411,889; 5,389,548 and 5,435,969) do teach monitoring by fluorescence in industrial water systems which may include water systems of the food processing industry. Yet in each of those patents, the material to be monitored is a water treatment agent such as a scale inhibitor, a corrosion inhibitor, a dispersant, a surfactant or an anti-foaming agent. However, none of these three patents directly address the particular problems of the food processing industry as disclosed herein.
Moreover, there is little reference to the use of fluorescence for the monitoring of food processing streams. A disclosure of fluorescence for the monitoring of glucose in food processes is U.S. Pat. No. 5,341,805. German patent DE 4234466 discloses a method for determining the concentration of a tracer-containing active agent in aqueous or non-aqueous active-agent solutions employed particularly in cleaning or disinfecting containers such as bottles, kegs, chests, and tanks and/or pipelines. Essentially, a method is provided wherein it is possible to determine the proper dosage of cleaning solutions utilized to clean food containers such that they are ready for use. That disclosure concerns packaging applications, and not the monitoring of food process streams during food production, as the instant invention. Therefore, there is a demand within the food processing industry for a rapid and efficient method for monitoring food process streams. The present invention fulfills these requirements.